s-8813 Seiko Instruments Inc., s-8813 Datasheet - Page 11

• Manufacturer Part Number: s-8813
• Description: 3-channel White Led Driver Ic Charge Pump Ic With Built-in Constant-current Circuit
• Manufacturer: Seiko Instruments Inc.

Rev.2.1
3. Constant current output circuit
The S-8813 Series features a three-channel constant current output circuit and enables driving of white
LEDs in the current mode.
In the case of the S-8813 Series, the constant current value can be controlled using one of the two
following methods according to the product.
In the case of the S-881300CPE, the desired constant current can be obtained with an external
resistance value. Since a reference voltage of 1 V ±2% is output to the RISET pin, application of
resistance R1 of 20 kΩ to 5.6 kΩ between the RISET pin and GND results in the flow of a constant current
of 50 μA to 178 μA in the current setting resistance (R
constant current 100 times and outputting it to I
between 5 mA to 17.8 mA/channel.
supplying the reference voltage to the VISET pin externally. Within the IC, a resistance of 10 kΩ is applied
between the VISET pin and GND. The application of a reference voltage of between 0.5 V and 1.8 V to
the VISET pin results in the flow of a current between 50 μA and 180 μA in the internal resistor (R
the I = V/R relationship. Amplifying this constant current 100 times and outputting it to I
I
On the other hand, a constant current of the desired value can also be obtained for the S-881300BPE by
OUT3
3-CHANNEL WHITE LED DRIVER IC (CHARGE PUMP IC WITH BUILT-IN CONSTANT-CURRENT CIRCUIT)
_00
can obtain a constant current of between 5 mA to 18 mA/channel.
+
−
1 V ±2%
reference voltage
−
+
Figure 8 Constant Current Circuit (S-881300CPE)
Figure 9 Constant Current Circuit (S-881300BPE)
1 : 100
1 : 100
R
2
=10 kΩ
Seiko Instruments Inc.
OUT1
IOUT1 (I
CPOUT
VISET (V
IOUT1 (I
IOUT1 (I
IOUT1 (I
IOUT2 (I
IOUT3 (I
CPOUT
RISET
R
, I
1
1
=5.6 kΩ to 20 kΩ
OUT2
) due to the I = V/R relationship. Amplifying this
, and I
OUT1
OUT1
OUT1
OUT1
OUT2
OUT3
VISET
C
V
C
V
CPOUT
OUT
CPOUT
OUT
=5.0 mA to 17.8 mA)
=5.0 mA to 17.8 mA)
=5.0 mA to 17.8 mA)
=5.0 mA to 17.8 mA)
=5.0 mA to 17.8 mA)
=5.0 mA to 17.8 mA)
=0.5 V to 1.8 V)
=10 μF
OUT3
=10 μF
=5.0 V
= 5.0 V
can obtain a constant current of
S-8813 Series
OUT1
, I
OUT2
2
) due to
, and
11